The present invention relates to vehicle electrical systems which comprise a generator including a voltage regulator and electrical components. Such electrical components include, but are not limited to, one or more stored energy sources, electrical loads such as instrumentation, electronic vehicle control systems, heating elements, lights, stereo systems, wiring system, and/or any other electrical device which may either supply or consume electrical energy to or from said vehicle electrical system. More specifically, the present invention focuses on a voltage regulator, including a system and method, which may be utilized in a vehicle electrical system to provide improved electrical protection, continued regulated operation, and warning to the vehicle electrical system even in the event of various electrical failures. The voltage regulator is configured to monitor, control, and protect said electrical components, generator, and its own system and operation, by including a monitor/control/protection (MCP) circuit and a field switching (FS) circuit. Of particular utility, said MCP and FS circuits are configured to discern and respond to various failure modes of the vehicle electrical system. The voltage regulator is further capable of reconfiguring its components to allow it to continue normal operation even when certain components fail to function properly. More specifically, the MCP circuit is capable of reconfiguring a protective component of the FS circuit to function as an operative component when the operative component of the FS circuit fails to function properly.
Vehicle electrical systems are normally comprised of electrical components, such as the above mentioned devices, and a generator including a voltage regulator. The generator supplies electrical power to the vehicle electrical system when the vehicle's engine is operating. The voltage regulator's primary function is to regulate the generator's output power at a specific reference voltage. Modern voltage regulators also function to monitor and control the generator's performance to protect the vehicle electrical system, see for example Becker et al., U.S. Pat. No. 6,184,661, and Jabaji, U.S. Pat. No. 5,907,233. It is desirable, however, to monitor and control not only the generator's performance, but also that of the voltage regulator and the rest of the vehicle electrical system, and further to be able to discern, respond, and communicate the failure modes of these components to the vehicle's computer network and/or the vehicle's operator. It is also desirable to be able to reconfigure the voltage regulator's components so that it may continue normal operation without the use of additional redundant components.
The generator converts an engine's mechanical power into electrical power. The engine's mechanical power, in the form of a torque at a rotational speed, is exerted on the generator via a coupling mechanism, such as a drive belt. When the generator's field coil conducts electric current while the rotor is turning, the stators experience changing magnetic flux that induces alternating electric current which is converted to direct current by rectifiers. The voltage regulator is designed to regulate the output power of said generator by switching on/off the generator's field coil. Specifically, the regulator seeks to maintain the generator output power at a specific operating voltage, for example 28 Volts. A vehicle electrical system is designed to operate within a designated range of this operating voltage, for instance ±0.5 Volts. Voltage variations beyond this envelope, signified as over voltage and under voltage conditions, may cause damage to the vehicle electrical system. Over voltage may burn electrical components, while under voltage may deplete the batteries to the point of disabling the vehicle.
Over voltage and under voltage conditions may occur as a result of a malfunctioning generator, voltage regulator, and/or faulty vehicle electrical components. Generator failure may occur as a result of a faulty field coil, stator winding, or diode trio, to name a few examples. Voltage regulator failure may occur as a result of a faulty switching transistor. A vehicle electrical circuit component, such as the cable connecting the generator to the battery, may result in an open battery circuit if it breaks or becomes unfastened due to excessive vibrations.
A common design of generators is such that the field coil is connected to the vehicle battery at one end, and grounded at the other end via a switching transistor included in the voltage regulator. The voltage regulator senses the generator output voltage and controls the field coil current to maintain a constant voltage according to the regulator's internal voltage reference as external electrical loads within the limits of the generator output power capacity are added and removed. This is generally achieved by making current flow through the field winding whenever output voltage drops below the reference voltage, and stopping the flow of current through the field winding whenever the output voltage rises above the reference voltage. The voltage regulator switches on/off the field coil by turning on/off its field switching transistor.
It is possible for the generator to cause an over voltage or an under voltage condition, irrespective of the voltage regulator's operating states. For instance, a generator whose field coil has made contact with the generator's frame may conduct field current to cause an over voltage condition even though the voltage regulator has turned off its field switching transistor. Alternatively, an under voltage condition may occur if the generator's stator windings or output connector develop a fault that reduces the generator output, even though the voltage regulator is performing properly.
It is similarly possible that the voltage regulator may cause an over voltage or an under voltage condition, irrespective of the generator's operating states. If a voltage regulator's field switching transistor fails in a short circuit mode it causes an over voltage condition. If a voltage regulator's field switching transistor fails in an open circuit mode it causes an under voltage condition. Such over voltage and under voltage conditions may occur even though the generator is properly performing its operation.
Although various systems have been proposed which touch upon some aspects of the above problems, they do not provide solutions to the existing limitations in monitoring, controlling, and protecting the vehicle electrical system. For example, the Renehan patent, U.S. Pat. No. 6,670,792 discloses electrical circuitry, apparatus, and methods of operation of said structures for regulating electrical power output by a generator via sensing current flow through the field coil of said generator, but does not provide the protection and warning capabilities of the present invention. The Karlich patent, AU 597900, discloses a voltage regulator circuit which includes an over voltage protection circuitry due to faulty wire connections, but does not discern and/or respond to other modes of failures. In Schramm et al., U.S. Pat. No. 5,162,720, the means for recognition of faults and protection includes an additional voltage regulator device, which is independent of the voltage regulator and operates in place of the voltage regulator when there is a defective connection in the voltage regulator, while in the present invention there is no need for an additional voltage regulator. Therefore, there is a need for a voltage regulator that can discern and protect against the vehicle electrical system failures. There is also a need for a voltage regulator that can reconfigure certain internal components in order to continue normal operation without implementing additional redundant systems. It is also highly desirable to have a warning and diagnostic system, incorporating visual indicators and communication lines, to provide descriptive system information for use by the vehicle's operator and computer network, respectively.
Modern vehicles rely heavily on their on-board electrical power generating device. A generator including a voltage regulator is such device. The voltage regulator functions to control and manage the electrical power generated by the generator. Vehicle electrical components may be damaged if either the generator or voltage regulator malfunctions. A voltage regulator that can properly protect against these malfunctions, irrespective of which device is the cause of the malfunction, and is able to reconfigure its components in order to maintain system operation under a variety of faults is desired. Furthermore, a voltage regulator that is capable of discerning and communicating vehicle electrical system failures to either the vehicle operator or computer network is needed.